Which species is it and are both the same species? I will guess that they are both H. carnosa and attempt to answer on this basis.

They like a degree of root restriction and are happy in the same pot for between two or three years before needing to be potted on. Allow to dry out well between watering with longer spells during winter months. Good light but not full sun so near a bright window. The peduncle that the umbel of flowers is attached to should be left on after flowering on all species as it extends a new ring of flower buds at the tip in succession, often many times. People who trying them for the first time sometimes don't realise this and unfortunately cut of the flower stalk (peduncle) and wonder why they get few or no flowers.

It may be that the other plant is a different form of the same species or indeed a different species and is just not so prolific? You don't of course say. They can be shy to flower but once they start, they tend to flower regularly after that.